In the spread spectrum communication system, it is necessary to set an appropriate threshold signal, following the correlator output signal level of the receiver, even if it varies, so that it is possible to detect the aimed correlation output signal.
As a prior art method, there is known a method disclosed e.g. in a Japanese patent application entitled "Spread Spectrum Receiver", filed by the assignee of the present application, Jan. 14, 1988 (Application No. 63-7144).
By this method, a positive and a negative polarity correlation spike outputted by a correlator are inputted to respective peak value detecting circuits to obtain peak values corresponding to the positive and the negative polarity correlation spike, which peak values are compared/selected, and a correlation pulse is outputted by obtaining threshold signals on the basis of the selected peak values to compare the threshold signals with the correlation spikes.
However, by this method, since 2 peak value detecting circuits as well as 2 comparing and selecting circuits were required for detecting the peak values of the positive and the negative polarity correlation spike. Therefore this method had a drawback that the spread spectrum communication device is complicated, which increases the number of parts, it is expensive and it consumes much electric power.